I see a lot of players maxing only Q or only E, but giving 3 early point to E and then switching to Q is the best choise: until level 6 you need to farm, and putting 3 point to E is the best way to do it, because during living shadow you are able to do it twice, and also 'cause of Q nerf.
Once you reach lvl 6 you have to maximize burst, and that's why we are maxing Q.

Pros:

• Great mobility
• You can escape while harassing/slowing
• Insane burst
• The only assassin who can kill a tank within few seconds
• He's freakin' cool
• Very good farmer and laner
• He can kill adcs very easily and then escape
• He scales very well in all phase of the game
• He also scales very well with the skill of the player
• Very nice snowballing

Cons

• Immunity spells completely counter you
• Hard to kill someone (unless fed) without ulti
• No hard CC
• CC during during ulti shut down your burst

Zed is an assassin mostly played mid.
He can easily push the lane and gank other lane, and that's your main role during laning phase.
In teamfight your role is to kill the adc or apc while doing some aoe damage with Q and E, and then repositioning with your W or flash if they are focusing you.

Lasthitting with zed is extremely easy, due to his passive ( Contempt For The Weak ).
For the first 2 level, until you take Living Shadow you have to focus on farming, and not much on harassing.
After level 3 you become a farming and harassing machine:
You have to put your living shadow close to the enemy, then E+Q to harass him and, if he get once again close to the shadow (or you simply want to push or lasthit a minion) you can use your E once again before the shadow fades off.

coming soon